[CHORE] Avoid isDefined duplicated reference, move it to twenty-shared (#9967)

# Introduction
Avoid having multiple `isDefined` definition across our pacakges
Also avoid importing `isDefined` from `twenty-ui` which exposes a huge
barrel for a such little util function

## In a nutshell
Removed own `isDefined.ts` definition from `twenty-ui` `twenty-front`
and `twenty-server` to move it to `twenty-shared`.
Updated imports for each packages, and added explicit dependencies to
`twenty-shared` if not already in place

Related PR https://github.com/twentyhq/twenty/pull/9941

packages/twenty-shared/src/index.ts

@@ -6,6 +6,6 @@ export * from './types/ConnectedAccountProvider';
 export * from './types/FieldMetadataType';
 export * from './utils/fieldMetadata/isFieldMetadataDateKind';
 export * from './utils/image/getImageAbsoluteURI';
+export * from './utils/isDefined';
 export * from './utils/strings';
 export * from './workspace';
-